Info on delrin

bscofield · Post by **bscofield** » Sat Feb 19, 2005 6:49 pm

I wanted to know more about how you all work with delrin tenons. How many of you do this? How exactly do you work with it?

As I understand the process it is like this:

1-drill the delrin's mortise in stem
2-drill delrin
3-epoxy delrin to stem

Do I understand this process correctly? Also, where do you get delrin? What lenghts does everyone recommend (i.e. how far into the stem should it go)? What should I look out for?

Thanks,

Ben

bscofield · Post by **bscofield** » Sat Feb 19, 2005 11:53 pm

What qualifies as a "plastics supply store?" I know what you mean, but nothing comes to my mind. Are there any chains like this?

Post by **KurtHuhn** » Sun Feb 20, 2005 12:43 am

I get all my delrin from onlinemetals.com.

I use a file to cut notches in the part of the delrin that's going to be epoxied to the stem. It heps the epoxy hold on to it - otherwise it will just slip right out of the stem after the epoxy cures.

marks · Post by **marks** » Sun Feb 20, 2005 8:55 am

I get Delrin (Acetol) from MSC. Delrin is the Dupont registered trade name for Acetol.

I use the 5/16 size for my tenons, so there is no need to turn the delrin down to a smaller size. You should be able to buy different diameters of delrin.

You do need to cut some grooves in the delrin and in the wall of the mortise you make in the stem (as Random and Kurt mentioned) and make sure you fill these up good with epoxy (no air pockets in the grooves). After curing, you will need to drill out the overflowed epoxy from the airway. To cut grooves in the mortise wall, I use a little bitty buzz saw dremel bit.

I vary how deep the mortise goes into the stem, depending on what I am planning on doing with the stem. For example, pipe 1004 on my web page has a fairly short mortise in the stem to accept the delrin. The other pipes pictured have a longer mortise inside the stem. (Pipe 1404 (the one I gave to Paul) has a turned tenon).

Regarding what Random wrote about air pockets, if you drill the draft holes into the stem and the delrin before you epoxy the delrin into the stem, there will be no issue with air pockets. As long as you are doing your drilling on a lathe (I use a self centering chuck), your holes will line up properly. I also cut the profile of the end of the delrin that is going into the stem at the same angle as the bit I used to drill the mortise in the stem. No gaps, and if I'm off slightly in the profile and there happens to be a small gap, the epoxy fills it. (that's why I have to drill out the epoxy from the draft hole after it cures).

Good luck

marks · Post by **marks** » Sun Feb 20, 2005 1:46 pm

random wrote:
marks wrote:Regarding what Random wrote about air pockets, if you drill the draft holes into the stem and the delrin before you epoxy the delrin into the stem, there will be no issue with air pockets.
Quite true. There are a couple of advantages to epoxying before drilling. One is that you don't have to have a lathe (as is Ben's case). Another is a precision matter most people probably don't care about.

marks wrote:As long as you are doing your drilling on a lathe (I use a self centering chuck), your holes will line up properly
Also quite true, IF you have a lathe, and IF you don't drill the mortise enough larger that there is tenon-mortise side-to-side play.

Whatever you consider to work, works.

I didn't realize Ben didn't have a lathe when I posted (he just asked how we did this, so I responded).

For what it is worth, I tried drilling the draft hole on a hand cut stem and delrin tenon on a drill press and the results were far less than satisfactory. Maybe it could be done with precision results on a drill press or some other type of device, but I did not consider the effort worth it, so I saved up and bought a lathe. Others may have better results than I did using something other than a lathe to do this work, and I defer to them on this topic.

Random, regarding your comment about "...being a precision matter..." I will assume that you are referring to the concentricity between the hole drilled into the delrin and the hole drilled into the stem (you referred to this in an earlier post). I have not had issues with this, but I try to use quality tools and a true stem blank. If the stem blank is not true, one can easily make it true prior to drilling, but, then again, this would seem to require a lathe.

Finally, when I am inserting the delrin into the mortise I have to press the delrin into the mortise with some sort of aid (a clamp, for example, or push it against the workbench). This is true even before I put a layer of epoxy on each piece. So, yes, this process works for me.

Ben, there is often more than one way to get a desired result. Hope you find this information helpful in the search for your chosen method.

bscofield · Post by **bscofield** » Sun Feb 20, 2005 1:58 pm

random, marks, kurt,

this information is all very helpful. Thanks. I guess I'll just have to experiment and see what process can be adapted to my prefab stems and delrin when I get some.

And dangit I thought I was going to be able to drive somewhere and get this stuff! Crap! Doesn't sound like it.

I hate waiting for shipping on stuff!

jbacon · Post by **jbacon** » Wed Feb 23, 2005 11:13 pm

is this the same process for either rod stock or a molded bit. kurt in another thread you said you are using delrin for all your stem work. i can see in a hand cut stem w/ no airholes that once you do drill the airway the bit misses the epoxy by miles. but if you use a molded stem and then drill out the excess epoxy.is it safe to do it this way. marks, kurt, any others -any thoughts. just trying in my minds eye the engineering of delrin in molded stems. or am i just being over cautious and parnoid
any thoughts would be helpful (yes sometimes i do inhale, but not too often)

thanks
jim

bscofield · Post by **bscofield** » Wed Feb 23, 2005 11:22 pm

jbacon wrote:is this the same process for either rod stock or a molded bit. kurt in another thread you said you are using delrin for all your stem work. i can see in a hand cut stem w/ no airholes that once you do drill the airway the bit misses the epoxy by miles. but if you use a molded stem and then drill out the excess epoxy.is it safe to do it this way. marks, kurt, any others -any thoughts. just trying in my minds eye the engineering of delrin in molded stems. or am i just being over cautious and parnoid
any thoughts would be helpful (yes sometimes i do inhale, but not too often)

thanks
jim

Jim, i'm pretty sure that people on here before have stated that it is safe for smoke to come into contact with dry epoxy.

bscofield · Post by **bscofield** » Thu Feb 24, 2005 10:24 am

that's funny... I went searching for the FDA thing and this is what I found:

http://www.newton.dep.anl.gov/askasci/c ... m03068.htm

Post by **KurtHuhn** » Sat Feb 26, 2005 3:13 pm

jbacon wrote:is this the same process for either rod stock or a molded bit. kurt in another thread you said you are using delrin for all your stem work. i can see in a hand cut stem w/ no airholes that once you do drill the airway the bit misses the epoxy by miles. but if you use a molded stem and then drill out the excess epoxy.is it safe to do it this way. marks, kurt, any others -any thoughts. just trying in my minds eye the engineering of delrin in molded stems. or am i just being over cautious and parnoid
any thoughts would be helpful (yes sometimes i do inhale, but not too often)

Exact same process. I use both molded and hand-cut stems, and use delrin tenons on both. I just prefer the way that delrin "feels" as a tenon.

I drill the draught hole in the tenon first, then drill it in the rod. If it's a molded stem, the draught hole is already there. Then I use a liberal amount of epoxy to make sure there are no air pockets, and then I drill out the excess epoxy after it has set.

It is very possible to be too cautious here. Don't try to over-think it, just get up and do it one day.

bscofield · Post by **bscofield** » Sat Feb 26, 2005 7:42 pm

how do you assure a flat stem face? Up until now my tenon cutter has been taking care of this... but if I use a delrin tenon how would I do this?

Post by **KurtHuhn** » Sat Feb 26, 2005 11:09 pm

I chuck the rod or molded stem in the lathe. With a molded stem, I use a cutoff tool to remove the existing tenon. Once the tenon is off, I treat it like a piece of rod stock - I flatten the face with a nice sharp forstner bit.

If you don't have a wood lathe (at a minimum) this will be much more difficult. It *can* be done on a drill press, but I sure wouldn't want to do it that way....

bscofield · Post by **bscofield** » Sun Feb 27, 2005 10:02 pm

For anyone else that's following the thread, I think I'm going to try and clamp the prefab bit and align it to where a guide bit flows straight through the airway. Then in that same position I'll just use a fostner bit to face it. All that before glueing it oughta do it... I think...

Or else I'm going to try and glue the delrin on and then run my tenon cutter over the delrin to face the stem...